Short-range phase coherence and origin of the1T−TiSe2charge density wave

Stripe and Short Range Order in the Charge Density Wave of 1T−CuxTiSe2

“…Each domain is locally commensurate, and the slight incommensurability reported in some bulk experiments [16,17] might result from the stacking along the c axis of such phase-shifted domains. A similar break up of the CDW into phase-shifted domains has been reported recently in Ti intercalated crystals [21] where the effect is observed already for 2% Ti content. In both cases, the 2 × 2 domain size is shrinking with an increasing number of intercalated atoms and the charge modulation period is independent of x.…”

“…[14]) and the formation of excitons is progressively suppressed. Ti doping, on the other hand, does not shift the chemical potential, leaving the excitonic pairing unchanged until the CDW domain size becomes smaller than the exciton Bohr radius thus abruptly suppressing their formation [21]. However, the exciton scenario is not compatible with the persistence of a clear local charge order observed by STM in crystals where the CDW phase transition is no longer detected by transport.…”

“…Single crystals were obtained after one week at 650°C for pristine (x ¼ 0) and 830°C for Cu intercalated specimen. These temperatures were chosen to limit the amount of Ti self-doping [9,21]. The single crystals were cleaved in situ at room temperature prior to the scanning tunneling microscopy (STM) and spectroscopy (STS) measurements (base pressure below 1 × 10 −10 mBar).…”

Local resilience of the 1T−TiSe2 charge density wave to Ti self-doping

“…Below T CDW ≈ 200 K, 1T -TiSe 2 exhibits a commensurate CDW phase with a 2x2x2 modulation and a weak periodic lattice distortion (PLD) [1]. Upon Cu intercalation [2], and under pressure [3], it can also host superconductivity that has been proposed to emerge in incommensurate CDW domain walls therefore reflecting the complex 1T -TiSe 2 phase diagram [4,5].Doping has shown to be an important tuning parameter of these collective mechanisms [1,2,6]. In particular, intercalation of Ti dopants, known to occur depending on the crystal growth temperature [1], leads to electrondonor impurity states close to the Fermi energy [7], enhances the Coulomb screening, and tends to reduce longrange electronic correlations.…”

“…Doping has shown to be an important tuning parameter of these collective mechanisms [1,2,6]. In particular, intercalation of Ti dopants, known to occur depending on the crystal growth temperature [1], leads to electrondonor impurity states close to the Fermi energy [7], enhances the Coulomb screening, and tends to reduce longrange electronic correlations.…”